The existence of long-lived galaxies lacking dark matter represents a challenge to our understanding of how galaxies form. Here, we present evidence that explains the lack of dark matter in one such galaxy: NGC 1052-DF4. Deep optical imaging of the system has detected tidal tails in this object caused by its interaction with its neighboring galaxy

Satellites orbiting disk galaxies can induce phase space features such as spirality, vertical heating and phase-mixing in their disks. Such features have also been observed in our own Galaxy, but the complexity of the Milky Way disk has only recently been fully mapped by Gaia Data Release 2 (DR2) data. This complex behaviour is mainly ascribed to

We present our analysis of the FLAMES dataset targeting the central 25' region of the Sextans dwarf spheroidal galaxy (dSph). This dataset is the third major part of the high-resolution spectroscopic section of the ESO large program 171.B-0588(A) obtained by the Dwarf galaxy Abundances and Radial-velocities Team. Our sample is composed of red giant

Context. Apparent deviations between properties of dwarf galaxies from observations and simulations are known to exist, such as the "Missing Dwarfs" problem, the too-big-to-fail problem, and the cusp-core problem, to name a few. Recent studies have shown that these issues can at least be partially resolved by taking into account the systematic

The periphery of the Small Magellanic Cloud (SMC) can unlock important information regarding galaxy formation and evolution in interacting systems. Here, we present a detailed study of the extended stellar structure of the SMC using deep colour-magnitude diagrams, obtained as part of the Survey of the MAgellanic Stellar History (SMASH). Special

The Large Magellanic Cloud (LMC) is the closest and most studied example of an irregular galaxy. Among its principal defining morphological features, its off-centred bar and single spiral arm stand out, defining a whole family of galaxies known as the Magellanic spirals (Sm). These structures are thought to be triggered by tidal interactions and

We collected over 6000 high-resolution spectra of four dozen field RR Lyrae (RRL) variables pulsating either in the fundamental (39 RRab) or in the first overtone (9 RRc) mode. We measured radial velocities (RVs) of four strong metallic and four Balmer lines along the entire pulsational cycle and derived RV amplitudes with accuracies better than 1

The Milky Way underwent its last significant merger ten billion years ago, when the Gaia-Enceladus-Sausage (GES) was accreted. Accreted GES stars and progenitor stars born prior to the merger make up the bulk of the inner halo. Even though these two main populations of halo stars have similar durations of star formation prior to their merger, they

We report the first APOGEE metallicities and α-element abundances measured for 3600 red giant stars spanning a large radial range of both the Large (LMC) and Small Magellanic Clouds, the largest Milky Way (MW) dwarf galaxies. Our sample is an order of magnitude larger than that of previous studies and extends to much larger radial distances. These

Due to their close proximity, the Large and Small Magellanic Clouds (LMC/SMC) provide natural laboratories for understanding how galaxies form and evolve. With the goal of determining the structure and dynamical state of the SMC, we present new spectroscopic data for ∼3000 SMC red giant branch stars observed using the AAOmega spectrograph at the

We use Gaia DR2 systemic proper motions of 45 satellite galaxies to constrain the mass of the Milky Way using the scale-free mass estimator of Watkins et al. (2010). We first determine the anisotropy parameter β, and the tracer satellites' radial density index γ to be β = $-0.67^{+0.45}_{-0.62}$ and γ = 2.11 ± 0.23. When we exclude possible former

Context. Isolated local group (LG) dwarf galaxies have evolved most or all of their life unaffected by interactions with the large LG spirals and therefore offer the opportunity to learn about the intrinsic characteristics of this class of objects. Aims: Our aim is to explore the internal kinematic and metallicity properties of one of the three

We report the discovery of two ultra-faint stellar systems found in early data from the DECam Local Volume Exploration survey (DELVE). The first system, Centaurus I (DELVE J1238─4054), is identified as a resolved overdensity of old and metal-poor stars with a heliocentric distance of ${\text{}}{D}_{\odot }={116.3}_{-0.6}^{+0.6}\,\mathrm{kpc}$ , a

The five globular clusters (GCs) of the Fornax dwarf spheroidal galaxy are puzzling for two reasons; the mass in GCs is high with respect to the galaxy's old stellar mass and their survival and large distance (>1 kpc) is at odds with naive expectations of dynamical friction. We present here a semi-analytic model, simultaneously addressing both

Context. Dwarf galaxies found in isolation in the Local Group (LG) are unlikely to have interacted with the large LG spirals, and therefore environmental effects such as tidal and ram-pressure stripping should not be the main drivers of their evolution. Aims: We provide insight into the internal mechanisms shaping LG dwarf galaxies by increasing

Using 3D positions and kinematics of stars relative to the Sagittarius (Sgr) orbital plane and angular momentum, we identify 166 Sgr stream members observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) that also have Gaia DR2 astrometry. This sample of 63/103 stars in the Sgr trailing/leading arm is combined with an APOGEE

We report a new star formation history for the Tucana dwarf spheroidal galaxy, obtained from a new look at a deep HST/ACS colour-magnitude diagram. We combined information from the main sequence turn-off and the horizontal branch to resolve the ancient star formation rates on a finer temporal scale than previously possible. We show that Tucana

We collected a large data set of field RR Lyrae stars (RRLs) by using catalogs already available in the literature and Gaia DR2. We estimated the iron abundances for a subsample of 2382 fundamental RRLs (∆S method: Ca II K, Hβ, Hγ, and Hδ lines) for which there are publicly available medium-resolution SDSS-SEGUE spectra. We also included similar

Context. Understanding the evolutionary history of the Magellanic Clouds requires an in-depth exploration and characterization of the stellar content in their outer regions, which ultimately are key to tracing the epochs and nature of past interactions. Aims: We present new deep images of a shell-like overdensity of stars in the outskirts of the

Time series observations of a single dithered field centred on the diffuse dwarf satellite galaxy Crater II were obtained with the Dark Energy Camera (DECam) at the 4m Blanco Telescope at Cerro Tololo Inter-American Observatory, Chile, uniformly covering up to two half-light radii. Analysis of the g and i time series results in the identification